"GRFN"@en . . "Grantham Formation And Northampton Sand Formation (Undifferentiated)"@en . . . . "stable"@en . . . . "174.7"^^ . "170.9"^^ . . "Calcareous sandstone, clay, ferruginous sandstone, ironstone, mudstone, sand and silty mudstone with subsidiary conglomerate. Bedrock. Occurs onshore. Formed during the Aalenian Age (Jurassic Period) (174.7-170.9 Ma BP)."@en . "Grantham Formation And Northampton Sand Formation (Undifferentiated)"@en .